Hi Tim, 12019637 is normally used on slimline models and is physically smaller than a 651956 which is used on full size models. Not sure about a 755078.
I fitted 12019637 as listed by Bosch for that model didn’t want to risk the wrong one.
It is actually the cheapest of the lot & was on a 60cm integrated.
Its about 10mm longer than the original & comes with a new cover that clips in the sump.